GHG Inventory in Waste Sector€¦ · Web viewThe mean annual global aggregate carbon emissions from anthropogenic sector for the 1990s have been estimated to be around 7.9 GtC

CONSULTATIVE GROUP OF EXPERTS ON NATIONAL COMMUNICATIONS FROM PARTIES

NOT INCLUDED IN ANNEX I TO THE CONVENTION

(CGE)

HANDBOOK ON THEWASTE SECTOR

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Consultative Group of Experts (CGE) – National GHG Inventory Handbook Waste Sector

CONTENTS

1 Background............................................................................................................5

2 Purpose of the handbook........................................................................................5

3 Organisation of the Handbook and Background Resources...................................6

4 Global Carbon and Nitrogen Cycle and the Waste Sector.....................................7

5 Revised 1996 IPCC Guidelines..............................................................................8

5.1 The approach adopted by the Revised 1996 IPCC Guidelines.......................85.2 Steps in the preparation of an inventory using the Revised 1996 IPCC Guidelines...................................................................................................................9

6 IPCC Good Practice Guidance ............................................................................10

6.1 Broad approach and steps.............................................................................106.2 Waste categories and GHGs.........................................................................10

6.2.1 Revised 1996 IPCC Guidelines and IPCC good practice guidance categories..................................................................................................................116.3 Methodological choice – identification of key categories............................116.5 Tier structure: selection and criteria.............................................................12

7 Comparison Between the Revised 1996 IPCC Guidelines and the IPCC Good Practice Guidance.........................................................................................................13

7.1 Approach and methods adopted .................................................................137.2 Key activity data required............................................................................137.3 Key emission factors required......................................................................147.4 Additional efforts and the rationale needed for adopting the IPCC good practice guidance......................................................................................................14

8 Reporting of GHG Inventory in the Waste Sector...............................................15

8.1 Mapping or linkage between the Revised 1996 IPCC Guidelines and IPCC good practice guidance.............................................................................................15

9 Methodological Issues and Problems in developing a GHG inventory for Waste using the Revised 1996 IPCC Guidelines....................................................................15

9.1 Problems relating to methodological issues.................................................159.2 Problems relating to activity data and emission factors...............................16

10 CH 4 Emissions from Solid Waste Disposal Sites.........................................................................17

10.1 Issues in estimating CH 4 emissions from Solid Waste Disposal Sites .......................... 1710.1.1 Methodological issues or problems relating to this category ............................. 1710.1.2 Issues relating to activity data and emission factors ........................................... 18

10.2 Addressing issues relating to activity data ..................................................................... 1810.3 Addressing issues relating to emission factors .............................................................. 1810.4 Sources of activity data and emission factors ................................................................ 18

11 Emissions from Wastewater Handling .......................................................................................... 18

11.1 Issues in estimating CH 4 emissions from wastewaters and N2O from human sewage ....................................................................................................................................... 18

11.1.1 Methodological issues or problems relevant to this category.............................19

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11.1.2 Issues related to activity data and emission factors11.2 Addressing issues relating to activity data ..................................................................... 1911.3 Addressing issues relating to emission factors .............................................................. 1911.4 Sources of activity data and emission factors ................................................................ 20

12 Emissions from Waste Incineration ............................................................................................... 20

12.1 Issues in estimating CO 2 and N2O from waste incineration ........................................... 2012.1.1 Methodological issues or problems relevant to this category12.1.2 Issues related to activity data and emission factors

12.2 Addressing issues relating to activity data ..................................................................... 2012.3 Addressing issues relating to emission factors .............................................................. 2012.4 Source of activity data and emission factors ................................................................. 21

13 Emissions from Waste Incineration ............................................................................................. 2113.1 Method of estimating and combining uncertainties ....................................................... 2113.2 Quality assurance and quality control ............................................................................ 22

13.2.1 QC procedures....................................................................................................2213.2.2 QA review procedures........................................................................................23

14 Emission Factor Database ...................................................................................................... 23

14.1 Features of the EFDB .................................................................................................... 2314.2 Steps involved in using the EFDB ................................................................................. 2414.3 Status of the EFDB ........................................................................................................ 24

15 Conclusions and Strategy for Future ..................................................................................... 24

16 Glossary ................................................................................................................................. 26

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ABBREVIATIONS

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AD – Activity DataEF – Emission FactorNAI – Non-Annex I

GHG – Greenhouse GasEFDB – Emission Factor Database

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1. Background

Article 4, paragraph 1, and Article 12, paragraph 1 of the United Nations Framework Convention on Climate Change (UNFCCC) establish that each Party shall develop, periodically update, publish and make available to the Conference of Parties (COP), information on its emissions by sources and removals by sinks of all Greenhouse Gases (GHGs), not controlled by the Montreal Protocol (GHG inventories), as a component of National Communications.

The COP adopted guidelines for the preparation of initial National Communications at its second session, by decision 10/CP.2. These guidelines were used by 106 non-Annex I (NAI) Parties to prepare their initial communications. At its fifth session, the COP initiated a process to revise those guidelines. New UNFCCC guidelines were adopted by the COP, at its eighth session, by decision 17/CP.8.

UNFCCC decision 17/CP.8 provides improved guidelines for preparing GHG inventory, which is reflected in <http://unfccc.int/resource/userman_nc.pdf>, to encourage the preparation and reporting of GHG inventory in an accurate, consistent, transparent, comparable and flexible manner. The UNFCCC has prepared a “UNFCCC User Manual for the Guidelines on National Communications from NAI Parties” to assist NAI Parties on the latest UNFCCC guidelines for National Communications, particularly in the preparation of GHG inventory.

More than 100 NAI Parties have used the Revised IPCC 1996 Guidelines for National Greenhouse Gas Inventories (hereinafter referred to as the Revised 1996 IPCC Guidelines) in preparing their GHG inventory. However, compilation and synthesis reports of NAI inventories have highlighted several difficulties and limitations in using the Revised 1996 IPCC Guidelines (e.g. FCCC/SBI/1999/11, FCCC/SBI/2003/13 and FCCC/SBSTA/2003/INF.10). The Intergovernmental Panel on Climate Change (IPCC) Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories (2000) (hereinafter referred to as the IPCC good practice guidance) has to some extent addressed some of the limitations and also provided guidelines for reducing the uncertainty.

This Handbook aims to assist NAI Parties in using the UNFCCC “User Manual for the Guidelines on National Communications from NAI Parties” and also provides an overview of the tools and methods available for inventory in the waste sector, as well as the UNFCCC inventory software for non-Annex I Parties.

2. Purpose of the HandbookFor the primarily biological sectors (two of the three waste subcategories) the GHG inventory is characterized by methodological limitations, lack of data or low reliability of existing data, leading to higher uncertainty. This Handbook aims to assist the NAI Parties in preparing GHG inventory using the Revised 1996 IPCC Guidelines and the IPCC good practice guidance, particularly in the context of UNFCCC decision 17/CP.8, focusing on:

- The need to move to IPCC good practice guidance and to higher Tiers or methods to reduce uncertainty;

http://unfccc.int/resource/userman_nc.pdf

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- A complete overview of the tools and methods;- Use of the UNFCCC inventory software and the IPCC emission factor

database (EFDB);- Review of activity data (AD) and emission factors (EFs), and options to

reduce uncertainty;- Use of key source category analysis, methodologies and decision trees.

The Handbook also addresses many of the problems encountered by the NAI experts during the course of using Revised 1996 IPCC Guidelines. These problems have been reflected in many documents of the Subsidiary Body for Implementation (SBI) (e.g. FCCC/SBI/1999/11, FCCC/SBI/2003/13) and the Subsidiary Body for Scientific and Technical Advice (SBSTA) (e.g. FCCC/SBSTA/2003/INF.10). The approach adopted to address these problems is as follows:

- The problems are reviewed and categorized into: i) methodological issues, ii) AD, and iii) EFs;

- The approach adopted by IPCC good practice guidance to overcome some of these problems is presented;

- Strategies for improvement in the methodology, AD and EF are presented;- IPCC good practice guidance strategy for AD and EF, according to the

three-tier approach is presented;- The sources of data for AD and EF, including EFDB are presented.

The target readers for this Handbook waste include:- NAI inventory experts;- CGE group members;- National GHG inventory team leaders.

Even where waste emissions are not explicitly requested by Table II of the former UNFCCC Guidelines (decision 10/CP.2), they have been reported by most NAI Parties because in some cases they may be the largest source of methane emissions and even the largest source from the inventory as a whole.

3. Organization of the Handbook and Background ResourcesThe Handbook has adopted the following approach and outline.

- Revised 1996 IPCC Guidelines; approach and steps- IPCC good practice guidance; approach and steps- Key source category analysis and decision trees according to IPCC

good practice guidance- Reporting framework for the waste sector under Revised 1996 IPCC

Guidelines and IPCC good practice guidance- Choice of methods – tier structure, selection and criteria- Review of the problems encountered in using Revised 1996 IPCC

Guidelines and how these are addressed in IPCC good practice guidance o Methodological issueso ADo EFs

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- Revised 1996 IPCC Guidelines category-by-category assessment of problems and IPCC good practice guidance options to address them

- Review and assessment of AD and EFs; data status and options- Uncertainty estimation and reduction.

The resources for the Handbook and for users of the Handbook involved in preparing the GHG inventory include:

- Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories <http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.htm>

- Good Practice Guidance and Uncertainty Management in National Greenhouse Gas Inventories <http://www.ipcc-nggip.iges.or.jp/public/gp/english/>

- EFDB – emissions factor database <http://www.ipcc-nggip.iges.or.jp/EFDB>

- Subsidiary Body for Implementation (SBI) <http://maindb.unfccc.int/library> and Subsidiary Body for Scientific and Technical Advice (SBSTA) <http://maindb.unfccc.int/library> documents.

The Handbook will focus on the approach for the preparation of the GHG inventory in the waste sector adopted by the Revised 1996 IPCC Guidelines. However, the Handbook attempts to incorporate the elements provided in the IPCC good practice guidance to address many of the problems in inventory preparation and to reduce uncertainty.

4. Global Carbon and Nitrogen Cycle and the Waste SectorGlobal carbon cycle: Carbon in the form of inorganic and organic compounds, as the greenhouse gases carbon dioxide (CO2) and methane (CH4), is cycled between the atmosphere, the oceans and the biosphere. The largest natural exchange occurs between the atmosphere and terrestrial biosphere, but human influence keeps growing, particularly since the industrial era.

Plants withdraw CO2 from the atmosphere through the process of photosynthesis. Carbon dioxide is returned to the atmosphere by the respiration of living creatures and the decay or incineration of organic matter; fossil fuel burning and land-use change being the main anthropogenic processes that release CO2 to the atmosphere. The mean annual global aggregate carbon emissions from anthropogenic sector for the 1990s have been estimated to be around 7.9 GtC. The waste sector contributes to CO2

emissions through waste incineration of inorganic matter when there is no energy recovery and it is a rather infrequent key source.

Some 10–23 per cent (IPCC, 2001) of annual global anthropogenic CH4 produced and released into the atmosphere is a by-product of the anaerobic decomposition of land-filled wastewater treatment may account for another 10 per cent of anthropogenic methane emissions, both from domestic and industrial waste sources. Industrial sources, pulp and paper as well as food and beverages processing industries account for most of the emissions.

http://maindb.unfccc.int/library

http://maindb.unfccc.int/library

http://www.ipcc-nggip.iges.or.jp/EFDB

http://www.ipcc-nggip.iges.or.jp/public/gp/english/

http://www.ipcc-nggip.iges.or.jp/public/gl/invs1.htm

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Global nitrogen cycle: Nitrogen in the form of inorganic and organic compounds, as in the greenhouse gas nitrous oxide (N2O), is cycled between the atmosphere, the oceans and the biosphere. The largest natural exchange occurs between the atmosphere and terrestrial biosphere, but human influence keeps growing, particularly since the industrial era (due to the use of fossil fuels, particularly in motors and urea production for agriculture).

Nitrous oxide emissions from human sewage or waste incineration are not generally considered important. For both of the above-mentioned sectors they represent less than 1 per cent of global anthropogenic N2O emissions.

Contribution of the waste sector: Changes due to waste management mainly affect CH4 emissions. The contribution of the waste sector to global CH4 emissions was estimated to be around 90 Mt annually during the 1990s. Solid waste management is usually the major source of methane emission from the waste sector.

The contribution of other gases is commonly smaller. These include: N2O, CO2 and Non-Methane Volatile Organic Compounds (NMVOCs).

A review of the National Communications of three developing countries – Cuba, Panama and Chile –which have prepared inventories in accordance with the Revised 1996 IPCC Guidelines for the year 1994 showed that the waste sector has significant impact on national CH4 emissions in developing countries (depending on the agricultural and land-use change and forestry emissions sectors) and could be a significant source of N2O.

5. Revised 1996 IPCC Guidelines

5.1 The approach adopted by the Revised 1996 IPCC Guidelines

The Revised 1996 IPCC Guidelines provide approaches, methodologies and technical guidance for preparing GHG inventories for the waste sector. The fundamental basis for the inventory methodology rests upon three assumptions; i) the flux of CH4 to the atmosphere is assumed to be equal to the sum of emissions from solid waste disposal sites, wastewater treatment and emissions from waste incineration (considered to be negligible); ii) the flux of N2O to the atmosphere is assumed to be equal to the sum of emissions from wastewater treatment and emissions from waste incineration; and iii) CO2 can be estimated by first establishing the rates of organic content in waste incinerated. This requires the estimation of the amounts and composition of waste and wastewater produced and treated each year, and the conditions in which the treatment is applied.

The Revised 1996 IPCC Guidelines provide a default approach, methodology and default data for the GHG inventory of the waste sector. The default approach involves estimating emissions using three categories, namely:

- Solid waste disposal on land – the most important effects of humans in terms of waste production are considered in a single broad category, which includes household, yard/garden and commercial/market as well as industrial waste if it is significant.Which subcategories are significant;

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- Wastewater handling – the CH4 emissions from activities that should be calculated separately are from domestic and commercial wastewater, as well as industrial wastewater, including sludge streams.

- Nitrous oxide from human sewage – which uses a method developed for the agriculture sector.

The Revised 1996 IPCC Guidelines briefly described general issues and methodological approaches for other possible categories, such as waste incineration, in which an indication is provided that if waste is used directly as fuel or converted into a fuel, the emissions should be calculated and reported under the energy sector. Carbon dioxide emissions from the decomposition of organic materials are assigned to the agriculture and Land Use, Land-Use Change and Forestry (LULUCF) sector. There is also a recognition that no method is provided to calculate emissions related to NMVOCs. Thus the inventory estimates:

CH4 emissions in the first two categories above; N2O from human sewage.

5.2 Steps in the preparation of an inventory using the Revised 1996 IPCC Guidelines

The approach, methodology and the steps involved in estimating emissions in waste sector, particularly for the NAI Parties using the IPCC default methods, are as follows:

- Step 1: Conduct a key source category analysis for the waste sector, where the sector is compared with others such as energy, industrial processes, agriculture, and LULUCF. Estimate the share of waste sector to national GHG inventory. Key source identification could be adopted by Parties which have already prepared their initial National Communications and have the inventory estimates. Parties which have not prepared the initial National Communications can use inventories prepared under other programmes (such as US Country Studies Program, ALGAS, UNEP etc.). Parties that have not prepared any inventory, may not be able to carry out the key source analysis.

- Step 2: Select the relevant categories, conditions and management systems.

- Step 3: Assemble the required AD depending on the tier selected, from local, regional, national and global databases, including the EFDB.

- Step 4: Collect EFs, depending on the tier level selected from local, regional, national and global databases, including EFDB.

- Step 5: Select the method of estimation based on the tier level and quantify the emissions for each category;

- Step 6: Estimate the uncertainty involved.- Step 7: Adopt quality assurance/quality control (QA/QC) procedures and

report the results.- Step 8: Report GHG emissions and removals, according to Revised 1996

IPCC Guidelines, Table 7.1.- Step 9: Report all the procedures, equations and sources of data adopted

for the preparation of the GHG inventory.

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6. IPCC Good Practice Guidance6.1 Broad approach and steps

The IPCC good practice guidance covers the waste sector and activities as described in Chapter 6 of the Revised 1996 IPCC Guidelines, creating a whole new section for emissions from waste incineration. The IPCC good practice guidance adopted a decision tree-based approach to organize the methodologies and good practices to prepare the GHG inventory and its uncertainties. Adoption of the IPCC good practice guidance approach involves reporting emissions from all categories and for all relevant GHGs, excluding NMVOCs. The approach for adopting the IPCC good practice guidance for preparation of the GHG inventory would involve the following steps:

1. Account for all categories and subcategories, all gases, depending on the key source category analysis;

2. Conduct a key category analysis; 3. Select the appropriate tier level/methodology for the key categories

and subcategories and gases based on the key category analysis, as well as resources available for the inventory process;

4. Assemble the required AD, depending on the tier/methodology selected, from regional, national and global databases;

5. Collect EFs, depending on the tier selected, from regional, national and global databases, waste inventories, national greenhouse gas inventory studies, field studies and surveys and the EFDB;

6. Select the method of estimation (equations), based on the tier level/methodology selected, and quantify the emissions for each category and gas. Adopt the default worksheet provided in the Revised 1996 IPCC Guidelines;

7. Estimate uncertainty;8. Adopt QA/QC procedures and report the results;9. Report the GHG emissions using the reporting tables;10. Document and archive all information used to produce the inventory,

including all the AD, EFs, sources of data, methods used, QA/QC procedures adopted for different categories and management systems and gases.

6.2 Waste categories and GHGs

The IPCC good practice guidance adopted two major advances over Revised 1996 IPCC Guidelines. They are:

i) Introduction of hierarchical tiers of methods that range from default data and simple equations to use of country-specific data and models to accommodate national circumstances;

ii) Inclusion of the waste incineration category.

The IPCC good practice guidance adopted three categories to ensure consistent and complete representation of main waste management categories, covering all the geographic area of a country:

- CH4 emissions are estimated for all the categories (in waste incineration, emissions are considered to be negligible);

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- N2O emissions are estimated for human sewage (no improvement since the Revised 1996 IPCC Guidelines) and waste incineration (new);

- CO2 emissions are estimated only for waste incineration (and only for organic material of fossil origin not used for energy purposes);

- NMVOC, remaining unaddressed.

6.2.1 Revised 1996 IPCC Guidelines and IPCC good practice guidance categories:

- There is a one-to-one linkage, or correspondence, between the Revised 1996 IPCC Guidelines categories and the IPCC good practice guidance categories.

- Additional categories (for waste incineration) are included in the IPCC good practice guidance.

6.3 Methodological choice – identification of key (source) categories

The IPCC good practice guidance identifies a key source category as “one that is prioritized within the national inventory system because its estimate has a significant influence on a country’s total inventory of direct GHGs in terms of absolute level of emissions, the trends in emissions, or both”. In this section, the term key category is used to represent the sources. Key category analysis helps a country to achieve the highest possible levels of certainty while using the limited resources for the inventory process. The decision about what tier to use and where to allocate resources for inventory improvement should take into account the key category analysis. Key category analysis is required to identify the following:

- Which categories are critical;- Which subcategories are significant;- Which gases are significant.

A GHG subcategory is significant if its contribution to the GHG emissions accounts for between 25 and 30 per cent of the overall waste sector inventory. The key category analysis given in IPCC good practice guidance is directly applicable to the categories used in the Revised 1996 IPCC Guidelines.

The key category analysis should be performed at the level of IPCC source categories (i.e. at the level at which the IPCC methods are described). The analysis should be performed using CO2 equivalent emissions calculated using the global warming potentials. The key category evaluation should be performed for each of the gases separately because the methods, EFs and related uncertainties differ for each gas. For each key category, the inventory agency should determine whether certain sub categories are particularly significant (i.e. represent a significant share of the emissions).

In this section a generic approach to key category analysis is given based on decision trees. As an illustration, a decision tree is presented to select which tier to apply on key source determination:

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6.4 Tier structure: selection and criteria

The Revised 1996 IPCC Guidelines introduced different levels of complexity at which national experts can work depending on the importance of the source category, availability of data and other capabilities. The IPCC good practice guidance provides users with methodological tiers for estimating GHG emissions for each source. The tiers defined by the IPCC good practice guidance nearly correspond to the levels of complexity given in the Revised 1996 IPCC Guidelines, though they were not referred to as ‘tiers’ (Revised 1996 IPCC Guidelines, Reference Manual). Tiers correspond to a progression from the use of simple equations or methods with default data through to country-specific data in more complex national systems. The tiers are summarized in Box 6.1. Tiers implicitly progress from least to greatest levels of certainty in estimates as a function of:

- Methodological complexity;- Regional specificity of model parameters;- Extent of AD.

BOX 6.1FRAMEWORK OF THE TIER STRUCTURE

Tier 1 approach employs the basic default method provided for the waste sector in the Revised 1996 IPCC Guidelines. Tier 1 methodologies usually use AD that are coarse, such as nationally available estimates of AD such as aggregate waste and wastewater statistics. Similarly the EFs could be sourced from global or regional databases. Tier 2 is only applied in waste for CH4 emissions from solid waste disposal sites using a different methodological approach (First Order Decay Method) as Tier 1 and applying AD and EFs which are obtained from national sources for several years.

Regardless of the tier level, countries should document which tiers were used for various categories as well as the EFs and AD used to prepare the estimate. For higher tiers, inventory agencies may need to provide additional documentation to support decisions to use more sophisticated methodologies or country-defined parameters. Moving from lower to higher tiers will usually require increased resources, and

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institutional and technical capacity. Higher tiers should be adopted for key categories, wherever possible.

7. Comparison Between the Revised 1996 IPCC Guidelines and the IPCC good practice guidanceThe IPCC good practice guidance is aimed at:

i) Overcoming the methodological limitations of Revised 1996 IPCC Guidelines;

ii) Preparing an accurate, consistent, complete, comparable and transparent inventory;

iii) Reducing uncertainty in the GHG inventory.

However, there is a difference between the Revised 1996 IPCC Guidelines and the IPCC good practice guidance with respect to:

- Methodological approach;- Categories included;- AD and EFs required.

In this section, the advancement or the differences between IPCC good practice guidance and Revised 1996 IPCC Guidelines are presented.

7.1 Approach and methods adopted

The difference in the approach and methods adopted by the Revised 1996 IPCC Guidelines compared with the IPCC good practice guidance are briefly presented in Table 7.1.

Table 7.1Comparison of methods adopted in the IPCC good practice guidance and Revised 1996 IPCC Guidelines

IPCC good practice guidance Revised 1996 IPCC GuidelinesFirst Order Decay method for solid waste disposal sites, based on real world conditions of decomposition

Based on the last year of waste entering to the disposal sites. Good approximation, only for long-term stable conditions. The First Order Decay method is mentioned without specific calculations

Includes a “check method” for countries with difficulties in calculating the emissions from domestic wastewater handling

Keeps a separation between: Domestic wastewaters Industrial wastewaters

Human sewage is indicated as an area for further development and no improvement is presented to Revised 1996 IPCC Guidelines

Calculation made on the basis of an approximation developed for the agriculture sector

New section including emissions from waste incineration. Covers:

CO2 emissions N2O emissions

No detailed methodologies were included.Some references were provided

7.2 Key activity data required

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Table 7.2 provides some examples of the differences in AD required for adopting the IPCC good practice guidance and Revised 1996 IPCC Guidelines. However, common AD required for both are not given in Table 7.2.

Table 7.2Examples of AD required for IPCC good practice guidance and Revised 1996 IPCC Guidelines

IPCC good practice guidance Revised 1996 IPCC Guidelines Disposal activity for solid waste for several

years

Less requirements with the check method for CH4 emissions from domestic wastewater

Top down modification for Revised 1996 IPCC Guidelines recommended due to high costs

Incineration amounts, composition (carbon content and fossil fraction) required for CO2

Emission measurements recommended for N2O

Disposal activity for current year, default values or a per capita approach

Wastewater flows and wastewater treatments data required

Industrial specific data very detailed required

No specific methodology specified

No specific methodology specified

7.3 Key emission factors required

There are a number of EFs common to both the Revised 1996 IPCC Guidelines and IPCC good practice guidance, such as: Methane Generation Potential for solid waste disposal sites, Human Sewage and Methane Conversion Factor.

However, there are additional EFs required for the IPCC good practice guidance approach, as in the Tier 2 method for the CH4 emissions from solid waste disposal sites using the First Order Decay method, e.g. the k value (no specific calculation methods or default values where provided by the Revised 1996 IPCC Guidelines).

7.4 Additional efforts and the rationale needed for adopting the IPCC good practice guidance

The adoption of the IPCC good practice guidance approach will lead to: an improved GHG inventory; reduced uncertainty; full and consistent representation of all emission categories; and consideration of all the relevant gases (based on key category analysis). This requires AD and EFs for the additional categories and gases included. However, adoption of the IPCC good practice guidance approach helps to use the limited inventory resources more efficiently by concentrating efforts only on the identified key (or significant) categories, gases and the relevant AD and EFs. The rationale for adopting the IPCC good practice guidance approach is justified by the following:

- Addresses most of the methodological limitations and inadequacies of the Revised 1996 IPCC Guidelines;

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- Adopts key category analysis, which enables dedication of limited inventory resources to key source categories and gases;

- Enables the estimation of emissions for all the relevant sources;- Reduces uncertainty in GHG estimates.

8. Reporting of GHG Inventory in the Waste Sector

8.1 Mapping or linkage between Revised 1996 IPCC Guidelines and IPCC good practice guidance

The IPCC good practice guidance uses the same tables as were provided by the Revised 1996 IPCC Guidelines, which is based on the same categories.

9. Methodological Issues and Problems in the GHG Inventory for Waste Using the Revised 1996 IPCC GuidelinesMore than 100 non-Annex I Parties have used the Revised 1996 IPCC Guidelines when preparing their GHG inventory and have reported as a part of their National Communications. UNFCCC (SBI and SBSTA) has been periodically compiling and synthesizing the information contained in National Communications from Parties not included in Annex I to the Convention. These compilation reports have periodically highlighted several problems related to methodological issues, AD and EFs as well as the approach adopted by the Revised 1996 IPCC Guidelines. The problems related to methodological issues, AD and EF are compiled and presented in sections 9.1 and 9.2 below, based on information from UNFCCC documents (FCCC/SBI/1999/11, FCCC/SBI/2000/15, FCCC/SBI/2001/14, FCCC/SBI/2002/16 and FCCC/SBI/2003/13 and FCCC/SBSTA/2003/INF.10).

9.1 Problems relevant to methodological issuesThe methodological issues largely relate to the following:

- Methodologies that are not covered, such as: sludge spreading and composting; the use of burning under conditions not reflected properly in the waste incineration section; the tropical condition of many non-Annex 1 Parties for Solid Waste Disposal Sites’ methane generation; the use of open dumps instead of landfills; the lack of a proper calculation method for human sewage in the case of island countries or countries with prevailing coastal population; and complexity of the methodology.

The following paragraphs present the methodological issues listed above and the approach adopted by the IPCC good practice guidance, along with additional options for improvement. Adoption of IPCC good practice guidance significantly reduces the problems related to the methodological issues. However, the problems related to AD and EFs remain for Revised 1996 IPCC Guidelines as well as IPCC good practice guidance approaches.

Problem 1: Lack of coverage of waste management methodologies that reflect national circumstances.

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The approach adopted by IPCC good practice guidance to overcome this problem and potential improvements are presented below.

IPCC good practice guidance approach Improvement suggested- The IPCC good practice guidance does

not cover composting and sludge spreading, which are common practices in NAI countries

- Burning and open dump processes are not well covered by IPCC good practice guidance and are frequent practices in NAI Parties

- Initiate field studies to generate methodologies, or use approaches proposed by Annex I Parties for these categories

- Expand the relevant sections to reflect the conditions prevailing in many NAI Parties

Problem 2: Different conditions than those presented in the methodologies

IPCC good practice guidance approach Improvement suggested- The IPCC good practice guidance does not cover conditions for tropical countries and their management practices in both solid wastes and wastewaters

- The approximation used to calculate nitrous oxide emissions from human sewage in the IPCC good practice guidance (the same as in the Revised 1996 IPCC Guidelines) does not reflect properly the situation of coastal/island areas

- Initiate field studies to expand the methodology

- Adopt the proposed methodologies covered in the agriculture sector, differentiating according to geographical reality

Problem 3: Complexity of methodology

IPCC good practice guidance approach

Improvement suggested

- The methodologies presented for Solid Waste Disposal Sites and Waste Incineration require data that is not commonly available in NAI Parties

- Methods similar to the Check method for wastewater shall be provided to enhance completeness of reporting

9.2 Problems relevant to activity data and emission factors

An examination of the problems encountered by the NAI experts relevant to AD and EF, as reported in several Compilation and Synthesis Reports of SBI and SBSTA are referred to in this section. The problems largely related to absence of data, lack of access to data, lack of processes to validate the data and high uncertainty. Some examples of the problems relevant to AD and EFs are listed below.

Examples: Activity Data Examples: Emission FactorsLack of data on generated solid waste

Inappropriate default values given in Revised 1996 IPCC Guidelines

Lack of time-series data for waste Default data not suitable for national

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generation circumstancesLack of availability of disaggregated data

Lack of EF at disaggregated level

Lack of data on composition of solid waste

Lack of availability of Methane Conversion Factors (MCF) for certain NAI regions

Lack of data on oxidation conditions

Low reliability and high uncertainty of data

Extrapolations based on past data used to apply Tier 2 for Solid waste Disposal Sites CH4 generation

Lack of EF for:- Waste incineration in Revised

1996 IPCC Guidelines (covered by IPCC good practice guidance)

Low reliability and high uncertainty of data

Default data commonly provides upper value, leading to over estimation

Approach adopted in IPCC good practice guidance: To minimize the uncertainty involved in inventory estimation originating from AD and EFs, the IPCC good practice guidance has provided multiple approaches:

- Key category analysis enables focusing of inventory efforts on the identified key categories, incorporating AD and EFs;

- Selective approach for choice of AD and EFs;- Additional default values for EFs;- Provision of improved sources of data, including EFDB.

The AD and EFs relevant to each of the Revised 1996 IPCC Guidelines categories are considered separately in sections 10–12, below. Higher tiers are recommended for key AD and EFs to reduce uncertainty and use the limited resources efficiently.

Improvements for the future: NAI Parties may have to initiate dedicated inventory programmes and provide infrastructural and technical support for sustained inventory processing. This may involve organizing periodic inventories, development of nationally relevant emission factors. It is likely that many countries may not have the resources needed to initiate these researches. Such countries may obtain data from other environmental or social studies. The limited resources could be efficiently utilized to minimize the uncertainty through adoption of key source category analysis.

10. CH4 Emissions from Solid Waste Disposal Sites

10.1 Issues in estimating CH4 emissions from Solid Waste Disposal Sites

10.1.1 Methodological issues or problems relevant to this category

This category is commonly a key source in many countries and in several cases is the main source of CH4 in the country. Accordingly, the Tier 2 methodology should be applied, but this approach is infrequent due to problems with AD, as discussed below.

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Another problem relates to the fact that some common practices in NAI Parties, such as the use of open dumps or open incineration in the waste disposal sites, are not well reflected in either the Revised 1996 IPCC Guidelines or in the IPCC good practice guidance. The fact that recycling (commonly of wood and paper but even of organic waste) is a common practice in NAI Parties, which occurs in many cases in an informal manner, needs to be reflected in future assessments preparing new guidelines.

10.1.2 Issues related to activity data and emission factorsThe main constraint for using Tier 2 is the lack of AD, both for the present and the required time series, for the waste flows and waste composition. It is worth to remember that the Revised 1996 IPCC Guidelines present default AD for only 10 NAI Parties. Also, the values reflected for a critical parameter for the application of the First Order Decay method, namely k, do not reflect the tropical conditions of temperature and humidity which prevail in many NAI Parties. The higher k value presented in the IPCC good practice guidance is 0.2 and the k value in the Revised 1996 IPCC Guidelines is 0.4.

The proposed Methane Correction Factor (MCF) even using the lesser value, 0.4, may lead to overestimations, due to the conditions of shallowness and the rather frequent practices of burning as a pretreatment in disposal sites.

10.2 Addressing issues related to activity dataThe provision of default values suitable for use by NAI Parties or a simplified methodology that is less data intensive will enhance both completeness and comparability. Some NAI Parties have prepared their own methodologies and those experiences may be shared.

10.3 Addressing issues related to emission factors

There is a need to develop parameter k values in NAI Parties. However, due to economic constraints, this will be more feasible if it is associated with projects or programmes for CH 4 recovery that will give additional inputs for the development of such research.

10.4 Sources of activity data and emission factors

The sources of AD for solid waste disposal in NAI Parties are not just related to the national or local governments that are dealing with the issue. Non-governmental organizations related to social or environmental work frequently address this theme and are a valuable source of AD in both quantities and composition. Academic or

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research institutions related to environmental, health or social issues are also frequently a good source of AD and, possibly, EFs.

11. Emissions from Wastewater Handling

11.1 Issues in estimating CH4 emissions from wastewaters and N2O from human sewage

11.1.1 Methodological issues or problems, relevant to this category Wastewater is a source of both CH4 and N2O emissions. For CH4 emissions from domestic wastewater handling, the IPCC good practice guidance presents a simplified method called “check method” which, in most cases, will be enough to avoid the complexities inherent in the Revised 1996 IPCC Guidelines. In NAI Parties, the availability of national methods or parameters, and even of AD is problematic. For CH4 emissions from industrial wastewater handling, the IPCC good practice guidance presents an example where these emissions represent a key source, recommending the selection of 3 or 4 key industries. For human sewage emissions of N2O, no improvements have been achieved since the Revised 1996 IPPC Guidelines, and this methodology presents several limitations that have made several NAI declare it as “inapplicable”

11.1.2 Issues related to activity data and emission factors As it is mentioned above, the lack of availability of AD and EFs is common in NAI Parties for CH4 emissions from domestic wastewater, and the “check method” may help to overcome this issue; even if it is not the case, the IPCC good practice guidance has provided some improvements by identifying the potential CH4 emissions. If industrial wastewater CH4 emissions is a key source category, it is feasible to work only with the largest industries. For N2O emissions from human sewage, the AD needed are relatively simple and easy to obtain.

11.2 Addressing issues related to activity data

Sources of AD and EFs in this sector are complex and scarce, as well as difficult to be obtained due to the differences in treatment, wastewater and conditions. The use of simplified methods – less data intensive is “check method” for CH4 emissions from domestic wastewater, top-down approach for industrial wastewaters and human sewage N2O emissions – are therefore recommended.

11.3 Addressing issues related to emission factors

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IPCC good practice guidance has provided a significant improvement by differentiating the Bo (maximum methane producing capacity) value for Chemical Oxygen Demand (COD) and Biochemical Oxygen Demand (BOD) in the case of CH4

emissions from domestic wastewater, even when, in NAI Parties, it is difficult to obtain data for any of those values. For this reason, the MCF remains the most complex issue to solve. Methane and N2O generation conditions for discharges into natural water bodies needs to be addressed in the future. In addition, the EF for human sewage N2O emissions needs to be carefully applied taking into account the fact that it represents a combination of two parameters: discharges to rivers and to estuaries.


A close collaboration with water quality/wastewater management authorities may provide data for the CH4 emissions from domestic wastewater. For the CH4 emissions from industrial wastewaters, a close collaboration with the experts calculating emissions from industry is highly recommendable. For human sewage N2O emissions, AD such as population and protein consumption are commonly available from national and international statistics.

12. Emissions from Waste Incineration

12.1 Estimating CO2 and N2O from waste incineration

12.1.1 Methodological issues or problems relevant to this category This category was only very briefly introduced in the Revised 1996 IPCC Guidelines, but is fully developed in the IPCC good practice guidance. In NAI Parties, the incineration of waste for purposes other than to destroy clinical waste is relatively uncommon, due to the high costs associated with incineration. The differentiation between CO2 and N2O is made because the former is calculated with a mass balance approach and the later depends on operating conditions.

12.1.2 Issues related to activity data and emission factorsIPCC good practice guidance recognizes the difficulties in finding AD to differentiate the four proposed categories (municipal, hazardous, clinical and sewage sludge) and does not request differentiation if data are not available if it is not a key source category (which, as stated above, is infrequent).

12.2 Addressing issues related to activity data

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In NAI Parties, the main AD required is incineration from clinical waste. However, due to the high costs associated with collection of data, this is often not accomplished even when legally required, and this fact may lead to overestimations in this category. It is recommended that Parties associate these emissions with pollution emissions that are commonly monitored.

12.3 Addressing issues related to emission factorsIPCC good practice guidance establishes EFs for different types of waste and incineration plants, but default values are only established for 5 out of 12 possible combinations and none of these cover the case of clinical waste, the most relevant category for NAI Parties.


Health authorities may be very relevant to the collection of AD, considering that for NAI Parties clinical waste is the most important category. For N2O emissions, direct measurements will be the most appropriate for NAI Parties.

13. Uncertainty Estimation and Reduction

The good practice approach for inventories requires that the estimates of GHG inventories should be accurate in the sense that they are neither over- nor underestimated as far as can be judged, and the uncertainties are reduced. The causes of uncertainty could include: unidentified sources, lack of data, quality of data, lack of transparency, etc. Uncertainty analysis involves:

- Identifying the types of uncertainties (measurement error, lack of data, sampling error, missing data, model limitations, etc.);

- Reducing uncertainties (improving representativeness, using precise measurement methods, correct statistical sampling method, etc.);

- Quantifying uncertainties (sources of data and information, techniques for quantifying uncertainty);

- Combining uncertainties (simple propagation of errors and Monte Carlo analysis).

The estimates of emissions arising from waste activities have uncertainties associated with:

- AD on quantities and composition;- EFs;- Management practices, etc.

13.1 Methods of estimating and combining uncertainties

The IPCC good practice guidance describes two methods for the estimation of combined uncertainties, namely Tier 1, simple propagation of errors and Tier 2,

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Monte Carlo analysis. The details of these two methods are given in IPCC good practice guidance. Use of either Tier 1 or Tier 2 uncertainty estimation provides insight into how individual categories and GHGs contribute to uncertainty in the total emissions in a given year. It is important to note that Tier 1 and Tier 2 methods of uncertainty assessment are different from the methods or Tiers (1 or 2) of inventory estimation. For example, a Tier 1 uncertainty assessment could be used by Parties adopting any of the tiers or methods for inventory estimation.

Tier 1 methods: The uncertainty associated with Tier 1 methods is likely to be high, because the suitability of the available default parameters to a country’s circumstances is not known. The application of default data in a country or region that has different characteristics from those of the source of the data can lead to large systematic errors. Ranges of uncertainty estimates for the emission factors are given in Chapter 5 of IPCC good practice guidance. Tier 1 is spreadsheet-based and easy to apply. Thus, all countries could undertake uncertainty analysis according to Tier 1 of uncertainty estimation, irrespective of which method or tier is used in the inventory process.

Examples:- Degradable Organic Carbon: –50 per cent to +20 per cent uncertainty;- Methane Generation Rate Constant: Uncertainty between –40 per cent and

+300 per cent;- BOD/person: Uncertainty between –30 per cent and +30 per cent.

Tier 2 methods – Estimating uncertainties by category using Monte Carlo analysis: This analysis is suitable for detailed category-by-category Tier 2 uncertainty assessment. In this method, country-specific data are used. These data are often only broadly defined. It is possible to assess the uncertainties involved due to the national circumstances, based on a few national level studies or direct measurements. Statistical packages are readily available for adopting the Monte Carlo algorithm.

Tier 3 methods: Extensive and representative country-specific information is used to estimate the emissions. The uncertainty with respect to AD, EFs (such as DOC, BOD) and the models adopted can be estimated using the methods described in the IPCC good practice guidance. The uncertainty of the GHG inventory estimate is likely to be low for countries adopting Tier 3 inventory methods; however the cost of implementing Tier 3 methods is likely to be very high.

13.2 Quality assurance) and quality control

The IPCC good practice guidance as well as the Revised 1996 IPCC Guidelines provide definitions and guideline for QA and QC, keeping in mind the need to enhance transparency and accuracy of the estimates of GHG inventory.

- QC is a system of routine technical activities to measure and control the quality of the inventory as it is being developed, and is designed to:o Provide routine and consistent checks to ensure data integrity,

correctness and completeness;o Identify and address errors and omissions;

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o Document and archive inventory material and record all QC activities.

- QA is a planned system of review procedures conducted by personnel not directly involved in the inventory compilation/development process.

13.2.1 QC procedures

Tier 1 - General QC procedures: It is good practice to implement the generic Tier 1 QC checks as outlined in IPCC good practice guidance. The general methods focus on the processing, handling, documenting, archiving and reporting procedures. An example of QC activity and procedure involves the following:

- Check the integrity of database files:- Confirm the appropriate data processing steps are correctly represented in

the database;- Confirm the data relationships are correctly represented in the database;- Ensure that data fields are properly labeled and have the correct design

specifications;- Ensure adequate documentation of database and model structure.

Tier 2 – Source category-specific QC procedures: Tier 1 QC checks relate to data processing, handling and reporting, whereas Tier 2 relates to category-specific procedures for key categories. Tier 2 QC procedures are directed at specific types of data used in the methods and require knowledge of:

- Source category;- Type of data available;- Parameters associated with emissions.

Tier 2 QC procedures should focus on the following types of checks (these are only examples; refer to Chapter 8 of IPCC good practice guidance for details):

- Check that no double counting or omissions have occurred; - Ensure completeness of source categories;- Check consistency of time series AD;- Check sampling and extrapolation protocols adopted.

13.2.2 QA review procedures

QA review procedures require an expert review to assess the quality of the inventory and to identify areas where improvements are necessary.

The Tier 1 QA procedure involves basic expert peer review by inventory agencies. Apply the review process to all source categories, particularly the key categories.

A Tier 2 QA procedure involves expert peer review, which includes:Review calculations or assumptions;Identify if the major models used have undergone peer review;Assess documentation of models, input data and other assumptions.

14. Emission Factor Database

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The EFDB has the objective to provide a variety of users, in particular the inventory compilers of the Parties to the UNFCCC, with current and well-documented EFs and other parameters, as well as to establish a communication platform for distributing and commenting on new research and measurement data. The EFDB is designed to be a recognized data repository where users can find EFs and other parameters with background documentation or technical references. EFDB is a database on various parameters to be used in calculation of anthropogenic emissions by sources and removals by sinks of GHGs.

14.1 Features of the EFDB

Some of the key features of EFDB are as follows:- EFDB is an online database;- It is continuously updated with data that is reviewed by a panel of experts;- It is menu driven and user-friendly;- It requires use of Internet Explorer version 5.0 or Netscape Navigator version 6.0 or higher coupled with Microsoft Office 97 for generating outputs in Word or Excel- It has multiple options such as:

o Step-by-step search using IPCC source category and gas;o Full text search using key words;o Find emission factor using unique ID.

However, the responsibility of using this information appropriately will always remain with the end users.

14.2 Steps involved in using EFDB

- Step 1: Selection of the sector, e.g. Waste (6)- Step 2: Selection of gases e.g. CO2, CH4, N2O- Step 3: Display the results- Step 4: Set the filter giving the conditions such as gas, parameter/condition,

region, etc.

Results are displayed along with the following details;- EF ID, gas, description, technologies/practices, parameters/conditions,

region/regional conditions, abatement/control technologies, other properties, value, unit, data provider, source of data.

14.3 Status of the EFDB for the waste sector

The EFDB is an emerging database, initiated in 2002. EFDB expects all experts to contribute to the database. Currently (year-2004), the EFDB has limited information for the waste sector EFs (Table 14.1). In future, with contribution from experts around the world, the EFDB is likely to become a reliable source of data for emission/removal factors for GHG inventory.

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Table 14.1Status of EFDB for waste sector – Number of records of emission factors

Revised 1996 IPCC Guidelines category Emission factor records

Solid Waste Disposal on Land (6A) 115Wastewater Handling (6B) 191Waste Incineration (6C) 47Other (6D) 0Total 353

15. Conclusions and Strategy for the Future

Over 100 NAI Parties have used the Revised 1996 IPCC Guidelines. Capacity-building has occurred in non-Annex-I Parties in using Revised 1996 IPCC Guidelines. NAI experts, as well as compilation and synthesis by UNFCCC have identified a number of issues and problems in using the Revised 1996 IPCC Guidelines. Some broad issues identified are:

i) Lack of clarity and inadequacies of the methods;ii) Lack of AD and EFs;iii) Low quality or reliability of AD and EFs;iv) High uncertainty of AD and EFs, leading to uncertainty in inventory

estimates;v) Non-suitability of default AD and EFs to national circumstances.

The IPCC good practice guidance attempted to overcome some of the methodical issues and problems involved in using the Revised 1996 IPCC Guidelines and suggested methods to reduce uncertainty. IPCC good practice guidance has not merely attempted to provide good practice guidance to the Revised 1996 IPCC Guidelines methods, but has gone beyond and suggested new methods. Adoption of the IPCC good practice guidance approach will lead to:

- Efficient use of limited inventory resources by adopting key category analysis;

- Reduction in uncertainty.

Thus adoption of the IPCC good practice guidance approach and methodology would be a significant advancement in making accurate and reliable estimates of GHG inventory, and to meet the requirements of CP8 decisions. IPCC good practice guidance contributes to overcoming the methodological problems. However, the problems relevant to AD and EFs may remain. The Parties may have to adopt twin strategies, namely:

- Firstly, build technical capacity and adopt the IPCC good practice guidance;

- Secondly, initiate the generation of a nationally derived database (for AD and EFs) and its validation (through QA/QC procedures) to help inventory process.

It is important to state that most of the AD and EFs required for the GHG inventory process are also required for environmental management and development programmes (e.g. monitoring of solid waste generated, domestic and industrial

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wastewater generation and incinerated waste, etc.). The NAI Parties could initiate measures to shift from Tier-1 methods to Tier-2 for Solid Waste Disposal Sites CH4

Generation, based on nationally derived AD and EF, to reduce uncertainty.

- Adoption of IPCC good practice guidance helps to shift to higher tiers by the adoption of higher tiers for key categories and gases only;

- Limited national resources could be allocated to key categories, to increase the efficiency of the use of limited resources;

- Focusing limited resources on generating nationally relevant key identified AD and EF.

The initiatives that are likely to contribute to the adoption of the IPCC good practice guidance approach and improved national GHG inventories of NAI Parties include:

- Development of Inventory Software for IPCC good practice guidance initiated by UNFCCC;

- Development of EFDB by IPCC and individual experts;- Capacity building activities for NAI in using IPCC good practice

guidance and generation of AD and EF;- Preparation of IPCC 2006 Guidelines.

16. Glossary

Waste Emissions – This includes GHG emissions resulting from waste management activities (involving solid and liquid waste management, excepting carbon dioxide from incineration of organic matter and/or used for energy purposes).

Source – Any process or activity which releases a greenhouse gas (such as CO2, N2O and CH4) into the atmosphere.

Activity Data – Data on the magnitude of human activity, resulting in emissions taking place during a given period of time. For example, data on waste quantity, management systems, and incinerated waste.

Emission Factor – A coefficient that relates activity data to the amount of chemical compound which is the source of later emissions. Emission factors are often based on a sample of measurement data, averaged to develop a representative rate of emission for a given activity level under a given set of operating conditions.

Documents

GHG Inventory in Waste Sector€¦ · Web viewThe mean annual global aggregate carbon emissions from anthropogenic sector for the 1990s have been estimated to be around 7.9 GtC